In cigarette lighters, it has long been known to use a flint, electric resistance heater or spark discharge, or external heat to ignite a fuel. Additionally, it is also known to use a self-burning gas, which ignites on contact with air, or a chemical catalyst which heats by reaction with a fuel gas and thus ignites the gas. Ignition methods which use neither electric spark discharge nor resistance heater are very convenient since nothing but fuel is required for their operation.
In the case of the self-burning or hypergolic gas, however, great care must be exercised to prevent leaks since spontaneous ignition of the gas upon exposure to the atmosphere can create a safety hazard. In the case of a lighter ignited by a catalyst, space must be provided for the chemical substance providing the reaction with the catalyst. The resulting extra volume is contrary to the desired small size of a pocket cigarette lighter.